This invention relates generally to induced draft furnaces and, more particularly, to a transition member for interconnecting an inducer housing discharge opening to a vent pipe for a condensing furnace.
In induced draft furnaces, a motor driven inducer blower is provided to enhance the mixing of combustion air with the fuel in order to better facilitate the combustion process. While the inducer may be located upstream and be of the blow-through type, it is more common to place it downstream of the combustion process so as to draw the supply air into the burner and cause the combustion gases to flow through the heat exchangers and the vent pipe to be discharged outside. With non-condensing type furnaces, the discharge air to the vent pipe is normally at a sufficiently high temperature that condensation does not occur within the vent pipe. However, with a condensing furnace, the temperature of the discharge gas in the vent pipe is sufficiently low that condensation is likely to occur. If such condensation runs back into the inducer, damage may occur.
One method of dealing with the condensate which forms in the vent pipe is shown in U.S. Pat. No. 4,603,680 issued on Aug. 5, 1986 and assigned to assignee of the present invention. The approach there is to include a trough structure that tends to collect the condensate running down from the vent pipe and then carry it away by way of a drain pipe. It has been recognized, however, that such an approach is not entirely satisfactory in that the condensate run-off from the vent pipe can be excessive enough that it overshoots the trough and enters the inducer device. Further, the problem is exacerbated by the recognition that any structure which is placed in the area between the vent pipe and the inducer must not interfere with or create undue turbulence in the flow of combustion gases therethrough.
Condensing furnace vent pipes are normally installed so as to come out the side of the furnace. For ease of installation, it may be easier to place the vent pipe through the top of the furnace; however, it is preferred that the top of the furnace be relatively unobscured by such piping to leave space for the filters or air cleaner assembly. Since the particular furnace installation requirements will vary with respect to the desirability for left or right side discharge, provision is normally made for installation in either direction by the serviceman in the field. This is commonly accomplished by the use of some type of transition device such as an inducer outlet box or assembly which is used to turn the flow of the discharge air from its upward path exiting the inducer housing, to a substantially horizontal flow to the vent pipe in either the left or right side. In order to ensure proper installation, it is desirable that such a structure be simple to install and not likely to result in leakage or undue turbulence. Further, in order to accommodate maintenance and repair services, it is desirable to provide for easy disassembly and reassembly of the device. For example, in downflow furnaces where the circulation blower is mounted near the top of the furnace, it has been found necessary to remove the inducer outlet assembly in order to gain access to the circulation blower assembly. The disassembly and reassembly process must therefore be relatively easy to accomplish.
In order to facilitate the simple and easy attachment of the inducer outlet assembly between the inducer and the vent pipe, it has been found that a single piece elbow is preferred. Attachment can be facilitated by the attachment of overlapping portions of the outlet assembly around corresponding overlapped portions of the respective inducer discharge end and the vent pipe. The connections can be secured, for example, by a simple hose clamp. In the case of the vent pipe, this can be easily accomplished since the vent pipe is commonly round, and therefore the round inducer outlet assembly can be easily clamped thereover with equal distribution of forces around the periphery. At the inducer discharge end, however, a problem was encountered because of the rectangular shape of the inducer discharge opening. The mating portion of the inducer outlet assembly could easily be made to fit the rectangular shape; however, a rectangular clamp tended to exert a relatively high pressure at the corners but insufficient pressure at the flat surfaces intermediate the corners, thereby allowing leakage.
It is therefore an object of the present invention to provide an improved inducer outlet assembly for accommodating the side discharge of exhaust gases.
Another object of the present invention is the provision for an inducer outlet assembly which prevents the flow of condensate from the vent pipe to the inducer housing.
Yet another object of the present invention is the provision for an inducer outlet assembly which offers a minimum restriction to the flow of exhaust gases therethrough.
Still another object of the present invention is the provision for an inducer outlet assembly which can be attached to a rectangular inducer discharge opening without attendant leakage.
Another object of the present invention is the provision for securing a rectangular inducer outlet assembly to a rectangular inducer discharge opening in such a manner that leakage does not occur therebetween.
Yet another object of the present invention is the provision for an inducer outlet assembly which is easy to assemble and disassemble.
Still another object of the present invention is the provision for an inducer outlet assembly which is easy to manufacture and effective in use.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.